Assessing the impact of the substantial equivalence mechanism on the cigarette and cigar markets - ABSTRACT Tobacco product brand/line extensions continue to proliferate as manufacturers seek to maintain or grow their market share. The Tobacco Control Act (TCA) introduced a number of potential pathways for marketing tobacco products, including a substantial equivalence (SE) process. Typically, SE determinations are made by comparing the “new” product to a pre-existing product in terms of design and emissions, with an eye toward whether the new product raises different questions of public health than what was previously on the market. The SE process raises important questions and concerns as to its impacts on the market and on public health. This understudied area of regulatory science could be leveraged by the tobacco industry to retain or attract consumers while avoiding the stricter regulatory standard applied to new products. Under the SE regulatory model in its present form, cigarettes and cigars can continue to evolve through accumulation of small changes and proliferation of line extensions that bear functional similarity to existing products. Notably, human studies are not explicitly required for SE determinations, which raises concerns as to whether a product that receives an SE Order on technical grounds is experienced in the same way as the predicate by consumers. Our Specific Aims are to evaluate the state of the market with respect to SE determinations and assess consumer product differentiation in two combustible tobacco product classes – cigarettes and cigars. These are the products of focus as they are clearly the most associated with health risks, and both of these markets were very well established prior to the TCA. In Aim 1 we will characterize the marketplace, leveraging Nielsen data and laboratory techniques to assess the design, contents, and emissions of 15 leading subbrands of cigarettes and cigars. In Aim 2 we will assess consumer behaviors with respect to substantial equivalence. In Study 2.1 we will leverage PATH data, which contains self-reported brands and sub-brands, to examine trends in the market share of brands. In Study 2.2, we will recruit a panel of adults (21+) who currently use one of the 15 leading subbrands of cigarettes and cigars as identified in Aim 1. The goal of this study is to examine whether consumers using these products can identify changes to their brand during the course of multiple year follow-up. In Aim 3, we assess industry behaviors with respect to substantial equivalence by compiling and integrating SE determinations and other orders posted on FDA’s website to examine trends in product characteristics and predicate product usage. A key goal is to determine if there are commonalities to what aspects of product design or emissions are changing, or if there are common predicate products employed. This proposal addresses the Product Composition and Design, Behavior, and Impact Analysis priority research domains.